David Lammy is exhausted. He says he hasn't slept for a week now. The member of parliament for Tottenham is still trying to make sense of the riots that started on his doorstep. "Complex" and "context" are words he returns to again and again.

We meet at Portcullis House, the office for more than 200 MPs, across the road from the Houses of Parliament. It's Thursday, seven days since Mark Duggan was shot by police in Tottenham and five days since the riots began. The mood is unusual for mid-August – a sombre hub of activity, an extra police presence, stringent security checks. We retire to a private office, with a view over the London Eye and the palace of Westminster – despite the famous view, it's bare and claustrophobic, not unlike a police interview room.

When did he first hear about the riots? No, he says, quietly, that's the wrong place to start. He was on holiday on the south coast with his family (he and the artist Nicola Green have two boys, aged five and three) when he was called by the borough's commander. There had been an "incident" 90 minutes previously; a man had been shot and killed by police. "I immediately came back to Tottenham because I knew it would be very sensitive, and I had to get on top of what had happened. And that meant going to the estate, and speaking to people on the ground. The statement I put out was that there was a mood of anxiety."

By the Friday, stories were appearing in the media – notably, that Duggan had fired first – that didn't accord with what Lammy was hearing locally. The mood in Tottenham grew darker.

What is astonishing, Lammy says, is that Duggan's family still had not been officially notified by police that he was dead. "I was in dialogue with the local police, and there was a lot of discussion with the Independent Police Complaints Commission (IPCC). I said I was worried that into the void would come rumour, and they needed to fill the void with fact about what happened." What was that rumour? "The rumour of Mark being shot outside the vehicle by police officers. I felt strongly the IPCC had to fill that void, and I spoke to them about accelerating the ballistics [report] on the bullets."

Still nothing happened. Friday turned into Saturday, by which time Duggan's family decided to go down to Tottenham police station for information or, rather, confirmation. They knew Mark was dead, it had been all over the news, but they had heard nothing from the police.

"Anyone who's a parent knows when your kids walk out of the home there's a tingle of fear that they might not come back and the police might come and knock on your door. That decency wasn't afforded to the Duggans. Somehow the IPCC taking over this investigation failed to communicate with the family in the initial stages. They say they thought the local police were doing that. The local police weren't doing that, and Scotland Yard certainly weren't doing that, so there's a gap into which these things fell."

At the police station, Duggan's family was kept waiting for five hours to see a senior officer. This was in the same area where, in 1985 Cynthia Jarrett collapsed and died during a raid on her home by Metropolitan police officers, who were searching for stolen goods following the arrest of her son Floyd, which led to infamous riots; where in 1999 the family of Roger Sylvester had protested about his death in custody. "Let's be clear: there is a history in Tottenham that involves deaths in police custody," Lammy says.

The temperature continued to rise, and within hours Tottenham was ablaze. First a police car was set alight outside the police station, then a second car and a bus, and before long the high street was on fire.

Had there been tension in Tottenham in the run-up to Duggan's death? "No. Prior to 6.10pm on Thursday, the mood in Tottenham was not any more or less tense than any other time. It was a normal Thursday in August."

So the riots were a result of poor policing? Again, he says, it's more complex than that. "For most members of the public it's just the police, but when you're dealing with the police on a day-to-day basis as I am, I recognise there are different bits of the police. This was an Operation Trident [set up to investigate gun crime in London's black community] run from Scotland Yard and I have learned over 12 years to be on my guard when there are operations from outside coming into my constituency. Because, over the years, it has been those operations that have tended to go wrong. It is clear to me that over the past 20 years the big development in policing has been community policing."

It seems that the police went from one extreme to another – from the ultimate heavy-handed approach to the ultimate hands-off. When the riots started, they simply watched as Lammy's constituency went up in flames. Rioters came from within the borough and from outside. Then they went to nearby Wood Green where there were no police officers.

"My constituents believe that those first skirmishes should have been snuffed out more quickly and that would not have led to the destruction . . ." His voice, so quiet a second ago, is rising as he talks. "Let's be clear: when people come into the area to go to Spurs they will see a devastation that we've never seen on a public high street." Now he's shouting. Lammy looks quite traumatised. "We had student protests in Whitehall a few months ago – hundreds of thousands more people – and the scale of destruction on Whitehall is nothing like the scale of destruction on Tottenham High Street so of course there is an issue about the nature of the policing that led to this."

Lammy was only 28 when he won a byelection after the death of Bernie Grant, still remembered as the firebrand who said local youths believed the police got "a bloody good hiding" following the Broadwater Farm riots of 1985 during which PC Keith Blakelock was killed. At the time, Lammy beat Grant's widow, Sharon Grant, to become the youngest MP in parliament. Now they are close friends. "I spend a lot of time talking to Sharon. She's been someone I've relied on a lot in the last few days because she knows what it means to be MP for Tottenham at a time like this."

At 39, he looks different from the chubby kid who entered parliament in 2000 – svelte and urbane, smart suit, flawlessly ironed white shirt, designer glasses. As he progressed through the Labour party, becoming minister for higher education, critics said they couldn't believe how rightwing he had become; how happy he was to do the Labour government's dirty work on, for example, asylum. But I'm not sure that's fair – he has always been a curious combination of conservative and radical, remaining in touch with his roots while embracing the mainstream.

Lammy prides himself on being a product of Tottenham. Like most of the locals he had a tough childhood – one of five kids, brought up by his mother Rose, shaped by the racial tensions and appalling policing of the 80s. "I remember the lead-up to the riots well . . . these were hot summers you were on the streets, I grew up on Dongola Road which is yards from the Farm, and I remember the stop and searches. I had a deep dread of the police, and the thing I feared most when growing up was going to prison because that seemed to be what was normal. And what was clear from the Scarman report and the Gifford report into the Tottenham riots, what happened was pitched battles between the second-generation black population and the police. There were no black police officers then." That at least, he says, has changed.

Lammy says his ambition as a child was to not end up in prison. And did he know he wouldn't? "No, I did not," he says stressing every syllable. "Absolutely not. None of us expected to succeed. Some did, but some of my contemporaries made their way to prison, some had mental health issues comes into their lives, many did not achieve their dreams."

What kept him going, he says, was his mother (who died three years ago) and role models in the community. "My mother was very hard working and very doughty. She was a home help originally, but managed to become a local government officer."

His mother would have been devastated by the last week, he says. And yes she would understand the many reasons behind the riots (class alienation, despair, fecklessness, boredom, criminality, copycat-ism, racism, for starters) but none of that would have justified it in her eyes. "She would say things like you can be poor, but you can still have pride. She would be so upset. So upset." He laughs. "She'd be like Pauline! Just like Pauline from Hackney. Watch her on YouTube it's the most wonderful thing. That would be my mother's view." (Grandmother Pauline Pearce resisted the rioters singlehandedly, telling them, "This is about a fuckin' man who got shot in Tottenham, this ain't about havin' fun on the road and bustin' up the place. Get real black people, get real . . . if we're fighting for a cause, let's fight for a fuckin' cause.")

As a boy, it was Lammy's voice that provided him with his freedom pass. He won a choral scholarship to the King's School in Peterborough where he became head boy. Even so, he wasn't a good scholar, and was expected to pass only two GCSEs. He surprised his teachers by passing nine, and never looked back. He graduated with a first-class degree in law from the School of Oriental and African Studies, did a masters at Harvard and was called to the bar in 1994. He doesn't think any of this would have happened without the singing scholarship. "We all need something where we can begin to feel a bit special. And there's a temporal quality to it that takes you beyond your immediate surroundings, which are not always fantastic. Certainly mine weren't."

But however impoverished the backgrounds of many rioters, Lammy is appalled by the notion that they don't know better. "Knowing poverty myself in the context of this country and also knowing poverty in the context of the country from which my parents come, Guyana, which is the second-poorest country in the western hemisphere . . . just because you're poor doesn't mean you can't know the moral difference between what is right and wrong. " Again this quiet man finds himself raising his voice. "I'm really worried the left want to leave that territory because you cannot cede that territory."

Yes, it's bullshit, I say. He nods ferociously. "Actually I'd quite like to use your word. It's bullshit. It's bullshit." It's quite shocking to hear Lammy swear – he's normally so restrained, so proper. "What are the two developments of the 20th century? The two big social developments of the 20th century that are, frankly, right in the lens not just of these riots but in the lens of the times we are living? One, of course, is neo-liberal economics begun by Thatcher and Reagan and ameliorated a bit but more or less adopted by Clinton and Blair, a laissez faire that basically says the market rules, which leads to a point of gross consumerism."

Didn't he buy into this?

"Hang on," he says. He's just getting into his stride. "And the second development of the 20th century is the huge advance in relation to social and cultural equality and rights that bring me here. Race, equality, women. Both are basically agendas of freedom, both are liberal in that sense, but that does not mean you have the freedom to do what the hell you want, and does not mean you have the freedom, for example to have children and absent yourself from parenting."

Fair enough, I say, but isn't Labour partly to blame for this culture of greed – after all, it was the Blair and Brown governments that were so intensely relaxed about private wealth and saw the the gap between poor and rich grew wider? Didn't his party let down those disenfranchised kids? "Well . . . yeah . . . pfffff." He exhales, blows on his lips. "I . . . I . . . never bought into Thatcherism." But I'm talking post-Thatcherism. "But equally if you are growing up in Tottenham through those 18 years by the end of that period you prayed for something different so of course many of us welcomed a Labour party that looked, as we ran up to 1997, as if it might be adopted by the entire country." Again, he exhales deeply. " So . . . Politics is the art of compromise."

What does he think Bernie Grant would have made of what's going on? "I don't want to speculate what Bernie would think, partly because he could be surprising in his views, and also as a thinking politician Bernie's views would evolve."

His phone rings. Lammy looks at it and laughs. "Oh, God, that's Sharon Grant. I must answer. Two seconds. 'Sharon, sorry I promise I'll call you back, thanks.'" If it was the police who got a good hiding in 1985, who did this time? "I'm not going to get into that language," he says. It's never been my style."

Lammy became friends with Barack Obama in 2005 at a reunion for Harvard alumni. They had much in common – black lawyers, raised by single mothers, in politics. Has he spoken to Obama about the riots? He squirms with embarrassment. "I haven't. I don't like to talk about my relationship with Barack."

While America has its first black president, at times British politics seems more monocultural than it was a few years ago. Why is there such a huge difference between the US and UK? Again, he says it's complex. "America and Europe are profoundly different. We need to understand the emphasis is not just on ethnic when we talk about ethnic minority, but on the minority too. Ethnic minorities in the context of any European country whether France, Britain or Germany will always be minorities, where as the context of Latinos and blacks in America almost gets you to a majority. So that makes it even more important to have visible role models here. And also there is the context of class. Europe has a deep history . . . the story of class is still evolving in Europe. People who were pretty pissed off about these issues in the past left and created America and Canada and Australia and the new world, and they have a different attitude to those issues – it is far more you can come from nowhere and run the country. Julia Gillard in Australia and Barack Obama have stories that don't stem from the elite. At this point in time, Britain is still absolutely a work in progress."

A few years ago Lammy was called the black Blair. More recently, he's been dubbed the British Obama. Does he really believe that we could see a non-white prime minister in the next few years? "You can't do my job and live in a pessimistic place." He smiles. "I am in the business of politics so I live in the groove called hope."

• This article was amended on 15 August 2011. The original incorrectly stated that the family of Cynthia Jarrett had "protested about her death in custody". This has been corrected.